1. Field of the Invention
The present invention relates to a roll comprising a roller mounted rotatably on a roller shaft. More particularly, it relates to a roll suitable to carrying an object with deviation preventing and expander actions.
2. Statement of Prior Art
An end-slenderized roller with the circumference decreasing toward both ends has action of preventing an object being carried from deviation from the roller surface. On the other hand, an end-thickened roller with the circumference increasing toward both ends has action of expander (U.S. Pat. No. 3,884,623). However changing circumference of a roller causes troubles such as wrinkles on the object being carried when the roller is a end-slenderized one, and deviation of the object from the roller surface when the roller is an end-thickened one. In addition, the curve on the roller surface in the length direction caused by the changing circumference can produce a distortion on the object being carried.
These points are same as for a roll comprising an end-slenderized or an end-thickened roller provided with a roller shaft. As rolls having rollers with changing circumference. known were those using straight roller shafts
(U.S. Pat. Nos. 1,317,713, 2,732,591, 4,068,360). These rolls are formed so that the roller rotates together with the roller shaft. It has also been proposed to arrange a pair of rolls having end-slenderized rollers oppositely into pinching system with the straight roller shafts curved by the load in directions opposite to each other. This opposite arrangement, however, can encourage meandering of the object being carried because the contact pressure between the rollers cannot be made constant in the shaft direction.